Liquid packaging pouches having a self-closable pouring spout formed by means of a flexible material such as a plastic film or the like, from which the liquid accommodated inside the pouch will not flow out once the spout has been closed, even if the pouch is suspended with the spout down, have been known in the past (for example, see Japanese Utility Model Application Laid-Open No. 62-93040 and the like). Furthermore, the self-closable spouts of these liquid packaging pouches are ordinarily formed by heat sealing plastic films, and the liquid accommodated inside the pouch is prevented from flowing out by forming the spout part into a V shape following closing.
FIG. 28 shows an outline of a conventional pouch having a self-closable spout and a manufacturing apparatus for the same. FIG. 28 (A) is a model diagram showing the essential parts of the pouch manufacturing apparatus, FIG. 28 (B) is a diagram illustrating the conditions of heat sealing of the pouch using the apparatus shown in FIG. 28 (A), FIG. 28 (C) is a model diagram showing the cross-sectional shape of a conventional pouch in a state in which the spout is closed, and FIG. 28 (D) is a model diagram showing the cross-sectional shape of a conventional pouch in a state in which the spout is open. In pouches that have a self-closable spout, the spout is conventionally formed as follows by heat sealing a plastic film: namely, as is seen in FIG. 28 (A), a non-pressing part 22 is disposed as a recessed hollow area that does not press against the plastic film in the heating part 21 of the heat sealing head that forms the spout, and an elastic pressing member 24 consisting of silicon rubber or the like, a glass cloth substrate 25 which is impregnated with Teflon, fired and coated on one side with a silicon type bonding agent, plastic films 26, 26 which constitute the pouch, and a glass cloth substrate 25 which is impregnated with Teflon, fired and coated on one side with a silicon type bonding agent, are successively placed on a pressing part 23 that faces the heating part 21 of the heat sealing head, the heat sealing head is closed, and the plastic films 26, 26 are heated and pressed by the heating part 21 and pressing part 23 so that these films are heat sealed, thus forming the spout.
In a conventional pouch manufacturing technique, as is seen in FIG. 28 (B), the elastic pressing member 24 is not pressed in the non-pressing part 22 of the heating part 21 of the heat sealing head during heat sealing; as a result, a heat sealing force is not uniformly applied in the boundary area between the heat-sealed part and the non-heat-sealed part. In the case of a conventional pouch with a self-closable spout that is manufactured in this way, as is shown in FIG. 28 (C), a very small gap 30 is formed in the unsealed state between the inside surfaces of the films 6 constituting the non-heat-sealed part 6 in the boundary area Y between the heat-sealed part 2 and non-heat-sealed part 6 forming the spout passage. In cases where a liquid with good wetting characteristics such that the wetting angle with the material forming the inside surfaces of the films is 90 degrees or less is accommodated inside the pouch, the following problem is encountered: namely if the pouch is suspended with the spout down after the spout 3 has been opened, contents such as the abovementioned liquid or the like leak out from the very small gap 30 as a result of the capillary phenomenon.
To describe this in greater detail, in the segment 5 (see FIG. 1) cut out from the spout 3 of the pouch perpendicular to the spout passage 4, as is shown FIGS. 28 (D) and 28 (E), the cross-sectional shape formed by the film inside surfaces is a curved shape that protrudes toward the outer surfaces (FIG. 28 (D)) or an irregular curved shape (FIG. 28 (E)) in the vicinity of the boundary area Y between the heat-sealed part 2 and the non-heat-sealed part 6. In the vicinity of the boundary area between the heat-sealed part and non-heat-sealed part of the spout passage, leakage of the liquid or the like occurs as a result of the presence of extremely small gaps as seen in FIG. 28 (c). Accordingly, in a conventional pouch, the occurrence of leakage of the contents such as a liquid or the like from the vicinity of the boundary area Y between the heat-sealed part 2 and non-heat-sealed part 6 of the spout passage 4 cannot be avoided.
Conventionally, meanwhile, a branched type pouch manufacturing method and apparatus have been proposed which allow the efficient continuous manufacture of various types of pouches such as branched self-standing pouches, pouches that have branched small compartments and the like, and that allow the continuous individual covering of the branched compartments with a packaging material that has barrier properties (Japanese Patent Application Laid-Open No. 11-70599). In this branched type pouch manufacturing method and apparatus, the pouches are continuously and automatically manufactured from a long body wall material in a state in which the body wall material feeding direction and the vertical direction of the pouch are perpendicular. A portion of the body wall material on at least one side is subjected to a first bend and a second bend along the feeding direction so that a pouch main body compartment, a first branched compartment and a second branched compartment are formed. The first branched compartment is used as a filling opening part, and the second branched compartment is used as a discharge opening part.
Furthermore, a packaging pouch which has a dispensing function is disclosed in Japanese Patent Application Laid-Open No. 11-193039. This packaging pouch is a pouch in which a conventionally used pouch container is provided with a constituent member consisting of a plastic film that has the function of a valve.
In the abovementioned Japanese Patent Application Laid-Open No. 11-70599, there is a disclosure regarding a manufacturing method for a branched type pouch; however, there is no disclosure regarding the continuous manufacture of a dispenser pouch with a dispensing function such as the abovementioned flat pouch, self-standing pouch or branched self-standing pouch, from a web-form packaging material. Furthermore, using conventionally known pouch manufacturing methods and apparatuses “as is”, it is not possible to manufacture, in a continuous process, pouches with a partitioning function that allows the contents accommodated inside the pouch to pass through, such as a dispensing function or the like.
Furthermore, in the manufacture of standing pouches, gazette pouches and the like, as shown in Japanese Patent Application Laid-Open No. 9-188311, for example, a technique is used in which a relatively broad web used as a bottom member that is bonded to the body member is symmetrically folded back on both sides and taken up in two rows on both sides of the center line of the web by using a forming plate so that both side edges abut against each other on the center line in the longitudinal direction. By thus folding back the bottom member as a single web, it is possible to simplify the pouch making machine; furthermore, the problem caused by the difference in tension of the respective bottom members in a two-row pouch making machine manufacturing pouches using two bottom members, i.e., the difficulty of accurate feeding of the two bottom members with respect to the body member, can be solved.
In this method in which the web is folded back, the forming plate is respectively constructed from a triangular part formed by a plane, and a rectangular part that is connected at an angle to the rear part with respect to the direction of flow of the triangular part. Accordingly, in the portion of the web that is folded back while the web travels from the triangular part to the rectangular part, a difference is generated in the length of the pass line in accordance with the position that is occupied in the lateral direction. As a result, if no countermeasures are taken, the generation of slack in the web cannot be avoided in the folding-back process. In order to eliminate this slack, a fixed tension that is determined by the amount of elongation is caused to act on the web passing over the forming plate. Accordingly, the folding back of the web must be performed while causing the tension to act on the web.
However, tension control that performs a fine tension adjustment that is used to load various portions of the web with a fixed tension is required during this web folding-back process, so that the folding back itself is difficult in the case of materials with a small elongation. Furthermore, a technique has also been proposed in which folding back is accomplished by lining up numerous rolls instead of using a forming plate; however, in this method as well, the slack that is generated in the web is handled by stretching the web by means of tension, so that similar problems arise. If the tension acting on the web is not uniform, then slack and wrinkles arising from this slack occur in the web, and if the pouch is manufactured by performing sealing with such wrinkles left “as is”, the manufactured pouch may have a distorted shape, and sealing may be incomplete so that the appearance and commercial value of the pouch deteriorate; in the worst case, the resulting product may be unacceptable as a pouch. Thus, the reason that slack is generated in the web in the folding-back process is as follows: namely, since differences that tend to be generated in the pass line passing through in the folding-back process in accordance with the position that is occupied in the lateral direction of the web are absorbed, the tension that acts on the web is non-uniform in the lateral direction of the web.